New toxins heighten need for feed tests

A survey of North America found 97 percent of samples tested positive for at least one mycotoxin

Feed grain samples were showing lower levels of mycotoxins late last year, but producers should remain vigilant for new toxins.

“2015 has definitely not been as bad, but people are more aware and they are looking,” said Dr. Barry Blakley, who heads the University of Saskatchewan’s toxicology laboratory.

Ergot continued to show up in feed samples from last year. As well, vomitoxin, known as DON, which is released by fusarium, has previously been known to present a risk, but new toxins identified as T-2 toxin and HT-2 have been discovered, said Blakley.

“Elevators are screening with Elisa kits for DON, but that is only part of the story,” he said. “DON is toxic stuff, but it is nowhere near as potent as HT-2, which is 50 times more potent than DON.… A lot of corn samples were loaded with T-2 toxins and HT-2 toxin, which we haven’t seen before.”

Ergot was more spotty in 2015, depending when crops received rain. It was a major problem in 2014. It has been found in all prairie provinces but nothing was detected in British Columbia.

The greatest ergot problems were in Ontario, followed by Manitoba and Saskatchewan.

More corn is being grown and more is being tested.

“Some of the corn cobs were absolutely loaded with mycotoxins, but if they make silage out of it that dilutes it and makes it below the level,” he said.

Blakley said crops should be analyzed in the form they will be fed, so stalks and cobs should be checked. Cattle will avoid them if they are contaminated.

Some grain may look fine but is loaded with mycotoxins.

Feed mills and producers have been more vigilant in testing samples, but many toxins grow in combination and may be missed in routine scans.

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Feed companies have been screening the components through Blakley’s lab to make sure all the ingredients are safe. They are also avoiding using screenings that could contain what looks like weed seeds but is actually ergot.

“A lot of companies are shying away from feeding the screenings and if they are, they are going to test it beforehand,” he said.

A broad survey across North America found 97 percent of samples tested positive for at least one mycotoxin, according to Alltech, the animal nutrition company.

Toxins were lower than last year, but it does not mean the risk is less, said Alexandra Weaver, a mycotoxin specialist with Alltech.

“They are found in all commodities, and since they are invisible and often odourless compounds, we must test for them to know where they are and what we have,” she said during a Nov. 30 webinar.

“Climate plays a very big role in the development of mould and myco-toxins. Depending on the rainfall and temperature during both flowering and harvest, this can have a very big impact whether there will be moulds that develop and grow and produce mycotoxins.”

Of the 100 samples from Canada and the United States, the greatest levels were found in the Midwest, the East Coast, Ontario and Quebec.

Fumonisin is a major mycotoxin derived from fusarium and affects grain crops.

“Fumonisins are very frequent in 80 percent of the samples we are seeing,” she said.

There were also positive cases of DON and fusaric acid because of fusarium infection of crops.

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Quebec grain had higher than normal levels of vomitoxin and zeralenone, which comes from fusarium. Animals may refuse to eat contaminated feed or they can become ill.

Monogastrics such as pigs and chickens can suffer overall negative effects with sickness and poor growth. Their intestinal tracts, internal organs and immune systems may be affected.

Vaccinations may not work properly in infected animals.

“Research show mycotoxins can influence intestinal diseases like necrotic enteritis (in poultry),” she said.

Producers have also been concerned about overheated greenfeed and hay because of the possible presence of nitrates, Alberta Agriculture forage specialist Barry Yaremcio said in an email.

Nitrates in greenfeed can be converted to nitrite if higher moisture bales become heated.

Nitrite is 10 times more toxic than nitrates.

Nitrite is formed when bale temperatures exceed 40 C during storage.  Nitrites require a different test than nitrates, so both need to be checked if bales have heated.

At these temperatures, some of the protein in the feed is bound to the fibre components and is not available to the animal.

A second test needs to be done to determine the available protein compared to the crude protein level, which is reported on feed test reports.

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